1. Field of the Invention
This invention relates to electromagnetic contactors and is directed more particularly to an electromagnetic contactor adapted for assembly without fasteners, such as screws or rivets, and a method for making same.
2. Description of the Prior Art
An electrical contactor is a switch that is adapted to open and close repeatedly to supply and interrupt electricity at power levels to electrical loads, such as motors and the like. An electromagnetic contactor is a contactor that is caused to operate by an electromagnet.
An example of eleotromagnetic contactors is given in U.S. Pat. No. 3,643,187 issued Feb. 15, 1972, in the names of James E. Stallman, et al., which teaches contacts that are brought into engagement by energizing an electromagnet and that are separated by the force of a spring when current is interrupted to the electromagnet. The apparatus disclosed in the '187 patent is assembled by screws and rivets, which renders a manufacturing process, including automatic assembly or assembly by robots, unduly complex.
U.S. Pat. No. 3,235,686, issued Feb. 15, 1966, in the names of Joseph J. Gribble, et al., discloses a contactor having facility for access to the contacts for service without disconnecting the power wires to the contactor. While such feature represents an advantage in operations, the device disclosed in the '686 patent is assembled by screws and is, therefore, difficult to assemble automatically.
U.S. Pat. No. 3,179,771, issued Apr. 20, 1965 in the name of Robert L. McGary, teaches an exposed external electromagnet and return spring. The structure taught in the '771 patent is assembled by screws and rivets and is difficult to adapt to automatic assembly.
U.S. Pat. No. 4,525,694, issued Jun. 25, 1985, in the names of William G. Dennison, et al., features a three-pole contactor that is assembled without the use of screws or rivets. The apparatus taught in the '694 patent has a separate mounting and supporting frame that is snapped to the housing of the contactor to facilitate mounting of the contactor. The '694 patent also features contacts held in place by a spring snap.
Pat. No. 4.951,018, issued Aug. 21, 1990 to James P. Schmiedel, et al., relates to an electromagnetic contactor adapted to be assembled without fasteners. In Schmiedel, a base or clip member snaps into a housing to hold components in the housing. The base or clip member is provided with two flexible prongs having oppositely-extending portions which snap into the housing. In an alternative embodiment, Schmiedel provides a housing with outwardly-protruding detents which snap into slots in a base member.